This Core unit provides a mechanism for coordinating the extensive clinical-epidemiologic studies required by several of the projects within the overall SCOR. It is responsible for the conduct of research in the special clinic-like setting utilized for the evaluation of participants in all of these projects. Most importantly, it allows coordination of the activities of these projects to make the most efficient use of the facilities which are available for the study of subjects in our epidemiological programs. It will also coordinate "outreach" visits to do follow-up evaluations on subjects who are enrolled in our longitudinal studies but have left southern Arizona.